Flash Floods Sweep Part of Long Island

Powerful thunderstorms brought torrential rain and flash flooding to Long Island early Monday, forcing multiple rescues and briefly closing parts of major highways leading to New York City. The National Weather Service issued a rare flash flood emergency during the worst part of the storm, describing it as a “particularly dangerous situation.”

The same storm system dumped nearly 10 inches of rain in some areas of Connecticut on Sunday, causing rivers to crest their banks and leading to another flash flood emergency declaration and about 100 evacuations, officials said. And in New York City, the downpour disrupted trains and forced the authorities to ground or cancel flights.

On Monday, more than 900,000 people in Suffolk County on Long Island were under a flash flood emergency that expired before dawn, according to the National Weather Service. A flash flood emergency is the highest level of flood warning.

Brian Ciemnecki, a meteorologist with the Weather Service in New York, said that it was rare to issue such an alert for the area and that weather officials made the call after receiving numerous reports of water rescues and other damage caused by the storm.

The rain in most parts of Long Island had stopped by early Monday, he said, but he expected lingering issues such as potential road closures, especially in the north half of the island.

A flash flood warning was in effect until 1:30 p.m. on Monday for a portion of southeast New York, including Suffolk County. Between six and 10 inches of rain had fallen in the affected area, officials said. The agency said early Monday that multiple rescues were ongoing in the Nesconset, Ronkonkoma, Smithtown and St. James areas on Long Island.